Hydraulic clutch



Aug. 23, 1932. G, H, WALKER HYDRAULIC -CLUTGH 5 Sheets-Sheet 1 Filed June 16. 1930 INVENTOR.

Aug. 23, 1932. G. H, WALKER HYDRAULIC CLUTCH s--seets-sheen Filed June 16, 1950 @www1 Aug. 23, 1932.

G. H. WALKER HYDRAULIC CLUTCH Filed June 16. 1930 Y3 Sheets-Sheet 3 lNVENTOR @Amftwzawd Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE GEORGE HENRY WALKER, F WORCESTER, ENGLAND, ASSIG-NOR TO HEENAN @a FROUDE LIMITED, 0F WORCESTER, ENGLAND HYDRAULIC CLUTCH Application med June 16, 1930, Serial No. 461,610, and :In Great Britain SeptemberI 7, 1929.

This invention relates to improvements in hydraulic clutches of the type described in the specification of my rior application Serial No. 331,358 filed anuary 9th, 1929,

` in which power is transmitted from the driv-` 15, emty.

ne object of the present invention is to provide means for controlling the rate at which liquid is allowed to leave the powerv transmitting portion of the clutch so that the amount of slip between the driving*l and driven elements can be regulated and a further object is to attain a better control of the rate of admission than has hitherto been attainable. A further object of the invention consists in providing the clutch with means for caus- .ing and controlling cavitation of the vortices which are created in the cups of the clutch elements by the circulation of liquid $0 which takes place under running conditions. The invention comprises twoA elements, a rotor and an outer casing both of which are adapted to rotate and which are formed with cups or ockets in which liquid circulates, passages eing formed in the vanes separating the cups for the admission of cooled liquid and a further passage or passages in one or more of the vanes by which the centres of the vortices can be placed in communication with the external atmosphere to vary the power transmitted by the clutch. ,v

The inventionwill be described with. reference to the accompanying drawings Fig. 1 is a verticalv section through the clutch. l

Fig. 2 is a part vertical section through the clutch showing means for preventing fluctuation in speed in one of the shafts.

Figs. 3, 4 and 5 are detail sections showing three forms of release valve.

Fig. 6 is a detail section of a modified declutching valve.

Fig. 7 is a part front elevation of a rotor member.

Fig. 8 is a section on line 8 8 Fig. 7.

Fig. 9 is a section on line 9-9 Fig. 8.

, In the arrangement shown in Fig. 1 the clutch B is mounted to transmit power from an electric motor shaft A or other lsource of power to a driven shaft C driving a fall or other machine (not shown) v The clutch B is formed with two elements B1, B2 of the type referred to in my prior application' Serial No. 331,358 led January 9th, 1929, with however a series of air vents b connecting the external atmosphere `with the centre of the vortices in the working compartment of the clutch where under running conditions the pressure is low.

When the cups of these elements are packed full of liquid, the clutch works at maximum eiliciency, transmitting power with a minimum amount of slip between the driving and y driven shafts. i

If however the clutch is allowed to empty itself partially the liquid which remains in circulation tends to cavitate and cling to the periphery of the cups while the cavity at the centre of the vortex becomes filled with atmospheric air admitted'through the vent pipes b. When running under this condition, the degree of slip between the driving and driven shafts is greater than if the cups remained full of liquid and by suitably controlling the admission and e ess of liquidl to and from the clutch, thecavltation and the amount of slip can be varied within wide limits. v

Liquid is admitted to the cups through an inlet pipe E passing through' inlet passages b1 in one'or more ofthe vanes separating the cups, the iow of liquid being controlled by hand operated or other valve e. The elements are lenclosed by a rotating cover plate B3 which is bolted to one of the elements.

In orderto prevent overheating -of the liquid, a circulation is provided by fitting the coverplate B3 with discharge plugs or Valves B4 fixed in any suitable position. Details of the discharge valves b are shown in Figs. 3 to 5 and will be described hereafter.

Hitherto it has been the practice .to arrangev such outlets at a point near the periphery where centrifugal force creates a pressure which was always assumed to be necessary to promote the escape of liquid.

It has been found however, that when transmitting power, the relative movement of the clutch elements generates a pressure of liquid which is additional to that created by centrifugal force, and tends to cause the liquid to fill all parts of the revolving clutch casing except those near the vortices where cavitation occurs. By taking advantage of this pressure and providing the outlets near the-'axis the edects of centrifugal force on the rate of discharge of the liquid are overcome.

The liquid after passing into the cups through the passages b1 overows during rotation of the members into the chamber formed between the walls of the element B2 and the cover plate B3 from which it is discharged when the pressure in this chamber has reached a predetermined value through the valves B4 into the stationary casing B5 from which it escapes through an outlet b2.

In operation the rate of feed is rendered uniform by supplying liquid to the inlets E and b1 at uniform velocity, by maintaining a uniform pressure at the intake and aI constant orifice or hand or otherwise controlled valve el in the inlet pipe E. The liquid is discharged from the clutch casin through the out-let valves B4 at a rate whic depends upon the pressure of liquid created inside the cover plate B3. This cover plate B3 is in free communication with the working compartments or cups; and as the pressure of liquid is primarily a function of the torque, if the torque rises in excess of the predetermined maximum, the pressure at the outlet valve B4 also increases and the liquid emerges more rapidly. Meantimefv there is no corresponding increase in the rate of supply, so that the clutch tends to empty itself and to reduce the torque transmitted, simultaneously allowing the slip to increase until the torque diminishes when `the original conditions are gradually restored. l

In addition to the outlet valves B4 one or more declutching valves b3 may be provided in the rotary casing at or near the periphery Y thereof. This valve b3 is preferably a spring loadedA ball valve which when the clutch is rotating is forced outwards by centrifugal force against the action of a spring b4 to close the orifice b5 in the casing thereby preventing the escape of liquid. Vlien the clutch is at rest the valves b3 are opened by the springs b4 allowing the liquid to escape from the chamber in the cover plate B3 to the stationary casing B3.

In a modication a balanced pressure piston valve may be employed in place of the ball valve b3. The valve b1 shown in Fig. 6 will close under centrifugal forcebut 1s unaffected by the pressure exerted upon it by the pressure of the liquid and will open even though the pressure of liquid within the clutch is relatively high.

The cover or casing B3 surrounding the element B2 is bolted to the element B1, hydraulic thrust washers bs being provided on the shaft C to form a bearing surface between the element-B2 and the casing B3. Passages b3 are provided between the cups in the element B2 and the faces of the thrust washers b3 to lubricate these faces. Y The passages are preferably formed in a direction substantially tangential to the periphery of the cup, so that the velocity head of the liquid coursin round the periphery of the cup is utilize to generate pressure in the annular space 68 somewhat in excess of that which exists inside the revolving casing. The liquid therefore tends to flow radially outwards between the thrust faces which are thereby lubricated.

In the form of the invention shown in Fig. 2 provision is made for counteracting the tendencyof one of the shafts to fluctuate in speed. v

A.- centrifugal pump D mounted on the shaft C is provided to supply Water to the inlet passages b1 in the vanes through passages b3. The pump D receives liquid from a chamber d supplied through a pipe d4- The quantity of liquid discharged b the pump is controlled by a valve d2 regu ating the area of ports formed in the body of the valve and therefore restricting to a greater or less degree the discharge of liquid into the inlet passages b3 and b4 of the clutch. Any convenient form of valve d2 may be utilized but the one shown is provided with a piston d3 capable of sliding in an axial ldirection so as to uncover more or less the valve ports. The piston d3 is pressed on to its seat by a spring d4 the compression of which can be regulated by a handwheel and screwed spindle d5.

Assuming that the shaft C is revolving at a given speed, receiving power through the clutch and that due to a change in load to which the shaft C is subjected, the speed of the shaft C tends to rise. The pump D will automatically run faster developing greater pressure and therefore supplying liquid more rapidly to the clutch than formerly, even though the ports in the main control valve remain unaltered in area. This action will result in the clutch receivinga greater supply of liquid and consequently transmitting more power but the effect of the spring loaded piston Z3 exaggerates this result because the piston, being subjected to the greater pressure of liquid, compresses the spring d* increasing the area for the iow o f liquid lll through the valve ports and the liquid iows into the clutch at a still greater rate. The tendency for the speed of the shaft C to increase is thereby checked rapidly.

Similarly, if the speed of the primary shaft tends to fall, the liquid pressure at the pump discharge nozzle falls, the area of the valve ports is also reduced and the flow of liquid into the clutch is quickly reduced, thereby diminishing the power supplied through the clutch to the shaft C. This again tends to stabilize the speed of the shaft C.

Details of three forms of discharge valve B4 in the casing B5 are shown in Figs. 3 to 6.

In Fig. 3 a ball valve f is held on its seat by a spring f1 the pressure exerted by the spring on the ball being varied by a screw f2 held in the desired position by a spring strip f3. In order to prevent the liquid discharged from the valve from being thrown against the periphery of the stationary casing B5 a ycurved guide plate f4 is provided surrounding the valve to direct the liquid inside a catch plate f5 mounted on the casing B5.

In Fig. 4 a spring loaded mushroom valve f6 is shown operated through a sliding sleeve on the shaft C by a forked lever f7 pivoted on the casing B5 this lever f6 being either manually controlled or by a governor (not shown) In the arrangement shown in Fig. 5 the liquid is discharged from the clutch through passageways g communicating with a passageway g1 in the centre `of the shaft C in communication with a radial passageway g2 and opening into an annular groove ga in a lantern ring g4 surrounding the shaft C1. From the lantern ring the liquid passes up the passageway g5 to a spring loaded ball valve g arranged to open at a predetermined pressure. After passing through the `valve\ the liquid escapes -into the interior of the casing B5.

What I claim as my invention and desire to protect by Letters Patent is 1. A hydraulic clutch of the type referred to for transmitting power comprising the combination with the driving shaft andthe driven shaft of a rotor mounted on the driving shaft, a rotor mounted on the driven shaft, cups in the first rotor and coacting -cups in the second rotor, vanes separating adjacent cups in the first rotor, vanes separating adjacent cupsY in the. second rotor, pas-.-

ing shaft, a rotormounted on the driven shaft, cups in the first rotor and coacting cups in the second rotor, vanes separating the adjacent cups in the first rotor, vanes separat ing the adjacent cups in the second rotor, passages formed in the vanes for the admis- Sion of cooled liquid, passages formed in the vanes for placing the centres of the vortices in communication with the atmosphere, a cover plate surrounding one rotor and bolted to the other rotor, a release valve adjacent to the axis of rotation and a pump to supply the liquid to the cups to' counteract fluctuations in speed in one of'theshafts.

3. A hydraulic clutch of the type referred to for transmitting power comprising the combination with the driving shaft and the driven shaft of a rotor mounted on the driving shaft, a rotor connected to the second shaft, cups in the first rotor and coacting cups in the second rotor, vanes separating the adjacent cups in theJirst rotor, vanes separating the adjacent cups in the second rotor, passages formed in the vanes for the admission of cooled liquid, passages formed in the vanes for placing the centre of the vortices in communication with the atmosphere, a cover plate surrounding one rotor and bolted to the other rotor, a release valve adjacent to the axis of rotation, a pump to supply the liquid and a declutching valve in the cover plate by which the clutch is emptied.

4. A hydraulic clutch of the type referred to for transmitting power comprising the combination with the driving shaft and the driven shaft of a rotor mounted on the driving shaft, a rotor mounted on the driven shaft, cups in the first rotor and coacting cups in the second rotor, vanes separating the adjacent cups in the first rotor, vanes separating the adjacent cups in the second rotor, passages formed in the vanes for 'the admission of cooled liquid, passages formed in the vanes for placing the centres of the vortices in communication with the atmos# phere, a cover plate surrounding one rotor and bolted to the other rotor, a release valve adjacent to the axis of rotation, a casing surrounding the rotors, a catch plate mounted on the casing to receive the liquid escaping through the release valve, a pump to supply liquid to the cups anda declutching valve in the cover plate by which the clutch is emptied.

5. A hydraulic clutch of the type referred to for transmitting power comprising the combination with the driving shaft and the driven shaft of a rotor mounted on the driving shaft," a rotor mounted on the driven shaft, cups in the first rotor and coacting cups in the second rotor, vanes separating adjacent cups in the first rotor, vanes separating adjacent cups in the second rotor, passages formed in the vanes for the admisj sion of'cooled liquid, passages formed in the vanes for placing the centres of the vortices in communication with the atmosphere, a cover plate surrounding one rotor, and bolted to the other rotor, a ball release valve adjacent to the axis of rotation, a casing surrounding the rotors, a catch plate mounted on the casing to receive the liquid escaping through the release valve, a pump to supply liquid to the cups anda declutching valve in the cover plate by which the clutch is emptied.

In testimony whereof I have hereunto set my hand this 23rd da of May, 1930.

' GEORGE NRY WALKER. 

